As a method of manufacturing an electronic product to be manufactured by solder joining a first joining member (e.g. a substrate) and a second joining member (e.g. an electronic component), there is a method achieved by supplying solder to the first joining member, placing the second joining member thereon, and heating them to be soldered to each other in a heater. In this solder joining using such heating method, however, holes (hereinafter, referred to as voids) may be generated in a solder joint portion. The presence of the voids may cause peeling of the joint portion or a decrease in heat conduction efficiency from the second joining member (the electronic component) to the first joining member (the substrate).
To avoid a deterioration in product quantity resulting from the voids, therefore, a decompressing type heater for solder joining under lowered pressure is sometimes used. Even if gas is taken in the solder and voids are generated under lowered pressure, the voids are contracted when the atmosphere is returned to atmospheric pressure by supply of inert gas or the like. A method of manufacturing an electronic product by solder joining under lowered pressure is disclosed in Patent Literature 1.